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| author | Christian Krinitsin <mail@krinitsin.com> | 2025-07-03 07:27:52 +0000 |
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| committer | Christian Krinitsin <mail@krinitsin.com> | 2025-07-03 07:27:52 +0000 |
| commit | d0c85e36e4de67af628d54e9ab577cc3fad7796a (patch) | |
| tree | f8f784b0f04343b90516a338d6df81df3a85dfa2 /results/classifier/gemma3:12b/assembly/1883984 | |
| parent | 7f4364274750eb8cb39a3e7493132fca1c01232e (diff) | |
| download | emulator-bug-study-d0c85e36e4de67af628d54e9ab577cc3fad7796a.tar.gz emulator-bug-study-d0c85e36e4de67af628d54e9ab577cc3fad7796a.zip | |
add deepseek and gemma results
Diffstat (limited to 'results/classifier/gemma3:12b/assembly/1883984')
| -rw-r--r-- | results/classifier/gemma3:12b/assembly/1883984 | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/results/classifier/gemma3:12b/assembly/1883984 b/results/classifier/gemma3:12b/assembly/1883984 new file mode 100644 index 00000000..1c571567 --- /dev/null +++ b/results/classifier/gemma3:12b/assembly/1883984 @@ -0,0 +1,27 @@ + +QEMU S/390x sqxbr (128-bit IEEE 754 square root) crashes qemu-system-s390x + +In porting software to guest Ubuntu 18.04 and 20.04 VMs for S/390x, I discovered +that some of my own numerical programs, and also a GNU configure script for at +least one package with CC=clang, would cause an instant crash of the VM, sometimes +also destroying recently opened files, and producing long strings of NUL characters +in /var/log/syslog in the S/390 guest O/S. + +Further detective work narrowed the cause of the crash down to a single IBM S/390 +instruction: sqxbr (128-bit IEEE 754 square root). Here is a one-line program +that when compiled and run on a VM hosted on QEMUcc emulator version 4.2.0 +(Debian 1:4.2-3ubuntu6.1) [hosted on Ubuntu 20.04 on a Dell Precision 7920 +workstation with an Intel Xeon Platinum 8253 CPU], and also on QEMU emulator +version 5.0.0, reproducibly produces a VM crash under qemu-system-s390x. + +% cat bug-sqrtl-one-line.c +int main(void) { volatile long double x, r; x = 4.0L; __asm__ __volatile__("sqxbr %0, %1" : "=f" (r) : "f" (x)); return (0);} + +% cc bug-sqrtl-one-line.c && ./a.out +Segmentation fault (core dumped) + +The problem code may be the function float128_sqrt() defined in qemu-5.0.0/fpu/softfloat.c +starting at line 7619. I have NOT attempted to run the qemu-system-s390x executable +under a debugger. However, I observe that S/390 is the only CPU family that I know of, +except possibly for a Fujitsu SPARC-64, that has a 128-bit square root in hardware. +Thus, this instruction bug may not have been seen before. \ No newline at end of file |